The two Koreas agreed to resume a high-level dialogue during a surprise and extremely rare visit to the South on Saturday by a top-ranking delegation from Pyongyang led by Hwang Pyong-So widely seen as the number two to paramount leader Kim Jong-Un.
The sudden visit followed months of military tensions and triggered hopes of a reboot for inter-Korean relations.
But South Korean President Park Geun-Hye and other senior officials, whilst welcoming the unexpected visit, stressed that it only marked a beginning.
Pyongyang still needed to demonstrate its willingness to improve inter-Korean relations through "sincere actions," she added.
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Park, who came to office in early 2013, has repeatedly said the door to dialogue with Pyongyang is open -- even a possible summit with Kim Jong-Un -- but insists the North must first take a tangible step towards abandoning its nuclear weapons programme.
The cash-strapped North has demanded that Seoul lift unilateral sanctions imposed after the sinking of the South Korean naval corvette Cheonan in 2010.
South Korea says the vessel was torpedoed by a North Korean submarine, but Pyongyang has always denied any involvement.
"Our government's basic position is that these measures can be lifted only after North Korea takes a responsible step that the South Korean people accept," Unification Ministry spokesman Lim Byeong-Cheol told reporters.